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bgp dampening
Enables/disables route dampening.
Syntax: [no] bgp dampening [route-map map-name] [half-life-time | reuse-value | suppress-value | maximum-suppress-time]
map-name
Name of route map that controls where BGP route dampening is enabled.
Default: disabled.
half-life-time
Defines the amount of time in minutes after which a penalty is reduced by half. Valid values are 10 - 45 minutes. Default: 15 minutes.
reuse-value
Defines the accumulated penalty amount at which the route is re-advertised. Valid values are 500 - 20000.
Default: 750.suppress-value
Defines the accumulated penalty amount at which the route is suppressed. Valid values are 500 - 20000.
Default: 2000.maximum-suppress-time
Defines the maximum time in minutes that a route is suppressed. Valid values are 1 - 90.
Default: 60 or 4 times the value of half-life time.
Description: When a route fails, a routing update is sent to withdraw the route from the network's routing tables. When the route is re-enabled, the change in availability is also advertised. A route that continually fails and returns requires a great deal of network traffic to update the network about the route's status.
Route dampening enables you to identify routes that repeatedly fail and return. If route dampening is enabled, an unstable route accumulates penalties each time the route fails and returns. If the accumulated penalties exceed a threshold, the route is no longer advertised. This is route suppression. Routes that have been suppressed are re-entered into the routing table only when the amount of their penalty falls below a threshold.
A penalty of 1000 is assessed each time the route fails. When the penalties reach a predefined threshold (suppress-value), the router stops advertising the route.
Once a route is assessed a penalty, the penalty is decreased by half each time a predefined amount of time elapses (half-life-time). When the accumulated penalties fall below a predefined threshold (reuse-value), the route is unsuppressed and added back into the BGP routing table.
No route is suppressed indefinitely. Maximum-suppress-time defines the maximum time a route can be suppressed before it is re-advertised.
Use the bgp dampening command with no arguments to enable BGP route dampening using the default values for half-life-time, reuse-value, suppress-value and maximum-suppress-time.
Use the bgp dampening command with arguments to override the defaults. If any argument is used, all the arguments must be defined.
Use the route-map keyword to associate a route-map to the dampening functionality. Only matching routes will be dampened according to the supplied parameters.
Use the no bgp dampening command to disable route dampening.
Factory Default: No route dampening configured. See the syntax description for the default values of the individual timers.
Command Mode: Configuration.
Example 1: The following example globally enables route dampening using the default values for all the arguments:
router(config)#bgp dampening
Example 2: The following example enables route dampening and sets the half-life-time to 20 minutes, the reuse-value to 1800, the suppress-value to 8000, and the maximum-suppress-time to 50 minutes.
router(config)#bgp dampening 20 1800 8000 50
Related Commands: show ip bgp
show ip bgp dampened-paths
show ip bgp flap-statistics
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Copyright © 2004
Avici Systems Inc.
Avici® and TSR®
is a registered trademark of Avici Systems Inc.
IPriori™, Composite Links™, SSR™, QSR, and NSR® are
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Source
File Name: BGP_Nd.fm
HTML File Name: BGP_Nd8.html
Last Updated: 05/10/04 at 16:36:55